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The line (1 + 2i)*z + (2i - 1)*conj(z) = 10i in the complex plane meets the imaginary axis at a point whose imaginary-axis intercept equals:

1. 5
2. 5/2
3. -5/2
4. -5

Correct answer: 5/2

Solution

Substituting z = x + iy reduces the line to a real linear equation; setting x = 0 gives y = 5/2 as the intercept on the imaginary axis.

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